Electronic and mechanical lock and key therefor

A locking device comprising:

• a mechanical lock operable with a key, said mechanical lock including an electrical contact for contacting with an electrical contact on said key;
• an electrical lock which is controlled by an electrical signal;
• electrical circuit means for generating said electrical signal for operating said electrical lock comprising:
• (a) a memory for storing the identity of each key which is authorized to operate said mechanical lock;
• (b) a microprocessor for reading the contents of said memory;
• (c) a power supply for supplying an operating current to said memory and microprocessor;
• and,
• (d) an interface for connecting said electrical contact of said mechanical lock to said microprocessor whereby said microprocessor can communicate with an electronic circuit on said key and compare data supplied by said key with data stored in said memory and supply said electrical signal to said electrical lock in response to said data comparison, wherein said electrical lock is placed in a locking state when said microprocessor detects a mismatch between data supplied by said key and data stored in said memory, and said electrical lock remains in said locking state without providing any subsequent electrical current to said electrical lock;
• a master key which can be inserted in said mechanical lock, which does not operate said mechanical lock, for programming said electrical circuit means comprising:
• an electrical contact which contacts said mechanical lock contact when said master key is inserted in said mechanical lock,
• a data circuit for supplying said data to said memory identifying each key of a set of keys which can operate said electrical lock;
• and
• a first set of keys which operate said mechanical lock and have an electronic circuit which contains a unique number corresponding to a number stored in said memory, said first set of keys including a contact member which contacts said mechanical lock contact when it is inserted in said mechanical lock, receiving an operating voltage from said electrical circuit means and supplying said number to said microprocessor so it can be compared with numbers stored in said memory to operate said electrical lock.